Datasheet

MCP40D17/18/19
DS22152B-page 30 © 2009 Microchip Technology Inc.
3.1 Positive Power Supply Input (V
DD
)
The V
DD
pin is the device’s positive power supply input.
The input power supply is relative to V
SS
and can range
from 1.8V to 5.5V. A de-coupling capacitor on V
DD
(to V
SS
) is recommended to achieve maximum
performance.
While the device’s voltage is in the range of
1.8V ≤ V
DD
< 2.7V, the Resistor Network’s electrical
performance of the device may not meet the data sheet
specifications.
3.2 Ground (V
SS
)
The V
SS
pin is the device ground reference.
3.3 I
2
C Serial Clock (SCL)
The SCL pin is the serial clock pin of the I
2
C interface.
The MCP40D17/18/19 acts only as a slave and the
SCL pin accepts only external serial clocks. The SCL
pin is an open-drain output. Refer to Section 5.0
“Serial Interface - I
2
C Module” for more details of I
2
C
Serial Interface communication.
3.4 I
2
C Serial Data (SDA)
The SDA pin is the serial data pin of the I
2
C interface.
The SDA pin has a Schmitt trigger input and an
open-drain output. Refer to Section 5.0 “Serial
Interface - I
2
C Module” for more details of I
2
C Serial
Interface communication.
3.5 Potentiometer Terminal B
The terminal B pin (available on some devices) is
connected to the internal potentiometer’s terminal B.
The potentiometer’s terminal B is the fixed connection
to the Zero Scale (0x00 tap) wiper value of the digital
potentiometer.
The terminal B pin is available on the MCP40D17
device. The terminal B pin does not have a polarity
relative to the terminal W pin. The terminal B pin can
support both positive and negative current. The voltage
on terminal B must be between V
SS
and V
DD
.
The terminal B pin is not available on the MCP40D18
and MCP40D19 devices. For these devices, the
potentiometer’s terminal B is internally connected to
V
SS
.
3.6 Potentiometer Wiper (W) Terminal
The terminal W pin is connected to the internal
potentiometer’s terminal W (the wiper). The wiper
terminal is the adjustable terminal of the digital
potentiometer. The terminal W pin does not have a
polarity relative to terminals A or B pins. The terminal
W pin can support both positive and negative current.
The voltage on terminal W must be between V
SS
and
V
DD
.
3.7 Potentiometer Terminal A
The terminal A pin (available on some devices) is
connected to the internal potentiometer’s terminal A.
The potentiometer’s terminal A is the fixed connection
to the Full Scale (0x7F tap) wiper value of the digital
potentiometer.
The terminal A pin is available on the MCP40D18
devices. The terminal A pin does not have a polarity
relative to the terminal W pin. The terminal A pin can
support both positive and negative current. The voltage
on terminal A must be between V
SS
and V
DD
.
The terminal A pin is not available on the MCP40D17
and MCP40D19 devices. For these devices, the
potentiometer’s terminal A is internally floating.